1900-1924
Willem A. Visser 't Hooft was born in Haarlem, Netherlands, on 20 September 1900. Like many early leaders of the ecumenical movement, he had his formative ecumenical experience in the Student Christian Movement.

After serving as chairman of the relief committee of the Netherlands Student Organization in the early 1920s, he took up an appointment on the Boys' Work staff of the World Committee for the YMCA in Geneva in 1924.

1925-1937
Visser 't Hooft's introduction to the wider ecumenical movement came in 1925 when he was named an alternate delegate for the YMCA to the Universal Christian Conference on Life and Work in Stockholm.

During the 1926 World Conference of the YMCA in Helsinki, he served as personal assistant to one of the founders of the modern ecumenical movement (and general secretary of the World Student Christian Federation (WSCF)), John R. Mott. There, as he wrote in his Memoirs, Visser 't Hooft was "instructed in the art of running a complicated world conference".

In 1925, during his first visit to the US (to work with Mott on the preparations for the Helsinki conference), he became interested in the "social gospel" movement. He wrote a critical study of it as his doctoral dissertation for the University of Leiden in 1928.

As general secretary of the WSCF from 1932 on, he made his first trip to Asia in 1933 to help organize Christian students there.

Visser 't Hooft attended both of the 1937 global ecumenical conferences where it was decided to form a world council of churches - the Oxford "Life and Work" meeting as part of the steering group and the Edinburgh "Faith and Order" conference as a member of the Executive Committee.

1938-1966
At the 1938 meeting in Utrecht where the World Council of Churches (WCC) was formed, Visser 't Hooft was named WCC general secretary of its provisional committee (despite the reservations of some that at 38 he was too young for the position). At its first assembly in Amsterdam in 1948, he assumed the general secretaryship of the WCC, and held that post until his retirement in 1966.

Visser 't Hooft chaired the steering committee for the world conference of Christian youth (Amsterdam, 1939), the last major international ecumenical event before the war. After the war broke out, he worked actively from Geneva to assist refugees from Nazi Germany and maintain liaison between churches in occupied territories and the outside world.

Beginning in 1948, his tenure as WCC general secretary involved him in endless travel around the world, making a vast number of personal contacts, lecturing and speaking on behalf of the Council and attending hundreds of meetings large and small.

He himself described the task of general secretary as one of administration, policy-making, liaison, interpretation and serving as chief of a large staff of men and women from many different national and confessional backgrounds. Central to this activity was his unwavering commitment to the unity of the church.

1967-1985
Following his retirement, Visser 't Hooft was elected honorary president of the WCC by its fourth assembly in Uppsala (1968). He remained in Geneva, which had made him an honorary citizen, staying active in the WCC until the 1980s, contributing to debates in nearly every meeting of the central and executive committees. He died in July 1985, three days after completing the second draft of a long survey of WCC-Roman Catholic relations from the 1929s to the present.

Publications:
Visser 't Hooft's literary output was staggering - including an estimated 50,000 letters. Among the more than 1500 items to appear under his name in printed or duplicated form were some 15 books in several languages.
Among his best-known books are:Memoirs, 2nd ed., WCC, 1987No Other Name: The Choice between Syncretism and Christian Universalism, London, SCM, 1963The Pressure of Our Common Calling, New York, Doubleday, 1959.